Technology for correcting distortion of an optical system for images of the surroundings of a vehicle is described in, for example, Japanese Kokai Patent Application No. 1997-159442. For the environment recognition device for a vehicle described therein, when an arithmetic operation is performed symmetrically to left/right images based on the image data read from the image memory, a correction coordinate table is set to store correction coordinates (Δx, Δy). These coordinates are prepared based on the distortion data of images obtained when the image of a checkerboard grid pattern as the object is taken by the optical part and the image pickup means. Then, by means of the corrected coordinates (X+Δx, Y+Δy) obtained by correcting the scan coordinates (X, Y) with the correction coordinates (Δx, Δy), a read image memory address is generated from the image memory. As a result, it is possible to avoid situations in which the image distortion cannot be handled based on distortion in the optical system.
In this reference, when distortion of the optical system is corrected by reading coordinates (X+Δx, Y+Δy) obtained by adding the address correction coordinates (Δx, Δy) read from the correction coordination table, the image can be read at the correct position coordinates. Then, an electric bulb is set at a known space position, and the deviation from the undistorted position is written as address correlation coordinates (Δx, Δy) in the table. The address correction coordinates are determined from measured data instead of from computations.